Digital techniques are currently being applied to transfer information in a variety of ways. One common way uses a facsimile, or "fax," machine to transmit a document from one location to another. Typically, the document is converted into a digital bitmap representation at the sending location. Next, bits in the bitmap are converted to an electrical signal and are transmitted, e.g., over a phone line, to the intended destination. At the receiving end the electrical signals are converted back into a bitmap representation of the original document and the bitmap is used to reproduce a close approximation of the original document on paper.
However, it is well known that the transmission of a document via fax results in a document of lesser quality at the receiving end. This is due to various factors including "noise" in the sending, transmitting or receiving mechanisms; smudges or stray marks in the original document, or low resolution in scanning the document at the sending fax machine. Prior attempts to correct these problems include approaches by Lim and Adachi (J. S. Lim, "Two-Dimensional Signal and Image Processing," pp. 570-575, Prentice-Hall, 1990; Adachi, Kawanishi, Kobayashi, "Improvement of Character Recognition and Generation Techniques in Facsimile Communication Systems," pp. 732-738, Proceedings Seventh Annual Joint Conference of the IEEE Computer and Communication Societies, 1988). Lim makes an analysis operating on page size units, while Adachi operates by smoothing the representation of individual characters.
Therefore, a method and system which provides for improved reproduction of the received document at the receiving fax machine is desired.